The present invention relates to a horizontal magnetic deflection linear amplifier of the type used in cathode ray tube (CRT) display systems.
A "flyback circuit" is a series resonant magnetic deflection circuit used to direct the position of the electron beam in a CRT. Such circuits provide a fast retrace of the electron beam from one side of the CRT to the opposite, "mirror image" position in one half cycle of oscillation, as determined by the yoke and flyback capacitor. They also have the advantage of consuming low power for the high retrace speeds they achieve. In a raster scan display system, such as a conventional television receiver, a flyback circuit is typically used to move the electron beam from the end of one line to the beginning of the next succeeding line. In a non-raster scan CRT system, such as a directed beam system, flyback is typically not used, because the electron beam is typically directed from one point to the next point, and the likelihood of movement between mirror image locations is not great. Thus, a typical directed beam CRT display system gives up the speed and power advantages of flyback.
Non-raster scan magnetically deflected CRT systems are often used in data display apparatus, such as patient monitors. In such systems, there are often a plurality of waveforms or other data displayed simultaneously on the CRT. In order to allow a single electron beam to produce the maximum brightness of the displayed data, the "off" time of the electron beam should be minimized. It is, therefore, desirable to be able to move the beam from point to point as quickly as possible. While a flyback technique is faster than linear movement for equal power consumption in the deflection circuits, it has heretofore been impossible to employ a flyback circuit in a CRT display system to produce a movement of the electron beam to a position other than its "mirror image" position.
It would be desirable to have a flyback circuit which could return to a position other than its mirror image position. It would also be advantageous to have a flyback circuit which could also operate in a linear, i.e., a non-flyback manner, when no flyback is required or possible.